Polymers are commonly used in water treatment equipment to aid in the removal of solids suspended in water. Ionic polymers, or polyelectrolytes, carry an electrostatic charge which attracts particles suspended in water and build a strong cell-like structure which permits mechanical dewatering of the solids in such a structure using pressure. Such dewatering apparatus includes belt presses and plate presses which carry filter media. Such apparatus is commonly known in the art and specific examples thereof will not be given herein. The filter media is typically a filter cloth of fine mesh material which allows water to pass therethrough and prevents solids from passing therethrough.
A common problem with the use of polymers in dewatering processes is that polymeric residues can contaminate hard surfaces and filter media in and around places where polymers are used. In some applications, the resultant residues can be removed through hard scrubbing and excessive water
rinsing, however such removal is difficult and time-consuming in as much as the polymers provide a sticky solution which is difficult to remove from the machinery. Furthermore, the wet residual polymer solutions are extremely slippery and are the cause of injuries to plant personnel due to falls.
As will be appreciated, deposition of the polymeric residue on the filter media results in a clogging or blinding thereof which greatly reduces the effectiveness of the filter material in producing dry solids. Accordingly operating costs of a plant with presses of reduced effectiveness are increased when the insufficiently dried solids must be recycled through the treatment facility. The blinding problem is intensified in applications where oil and/or grease is deposited in solutions with the polymer residue.
High pressure rinses have been installed in the dewatering apparatus to attempt to flush the contaminants from the filter media. However rinsing does not totally remove the polymer/oil and grease problem. Also methods of applying polymer cleaners using brooms and hand-held sprayers have not been known to achieve a clean deposit-free filter and as noted above are unsafe and time-consuming. Using currently known methods, filter media must be replaced after a short period of time at considerable cost in labor and materials as well as down time for the equipment.